Ultrasound devices are widely known and used in a variety of applications, including a number of specific applications in the medical field. In some medical applications, the ultrasound probe is positioned on the skin surface of the human body, while in other cases, the probes are designed to be inserted into openings in the human body, such as for instance the rectum, in the diagnosis and treatment of prostate cancer. In such applications, there is a need for an inexpensive, single-use cover for the ultrasound probe, as discussed in more detail below.
The cover must be easy to put on the probe and remove therefrom and be very inexpensive. Further, it must be waterproof and tough enough to reliably withstand the single use without tearing or breaking. In many cases, a very thin elastic rubber member, such as a conventional condom, is used. The condom cover protects both the probe and the patient as well as providing a capability for having water or other fluid around the tip of the probe. Having fluid around the tip of the probe is important, as it improves the transmission of the sound waves to and from the tissue of interest, and thus improves the image quality.
A significant disadvantage of such a cover arrangement, however, is that fluid initially present at the distal end of the condom cover, at the tip of the probe, is forced away from the tip of the probe, toward the proximal end of the probe cover, during insertion of the probe into the rectum of the patient.
Some manufacturers have attempted to solve this problem by having a channel in the probe itself, extending from the proximal end to the tip. Water is then injected through the probe into the space between the cover and the probe tip. While this arrangement improved the contact of the probe with the rectum, it often resulted in distortion of the prostate, particularly at the apex portion thereof. This distortion is quite disadvantageous relative to treatment of prostate cancer using radioactive seed therapy, which requires an accurate and undistorted image of the prostate.
Most of the modern ultrasound probes do not have such a fluid channel. Therefore, if fluid is to be used to improve signal transmission in current probes, the technician must put the fluid into the condom prior to securing it to the probe. As indicated above, however, in the process of inserting the probe with the cover into the rectum, most if not all of the water initially present at the tip of the probe is forced rearwardly to the proximal end of the cover. This eliminates the possibility of improved transmission resulting from fluid at the tip of the probe, because of the movement of the fluid to the proximal end of the cover.
The "bunching" of the fluid at the proximal end of the probe can also result in the insertion of the probe being more difficult and can further result in tearing of the cover, as well as other disadvantages.
Hence, it is desirable to have an ultrasound cover which has the physical characteristics of a conventional condom, but which is adapted so that fluid can remain near the distal end of the probe, without distorting the prostate, during insertion and retraction of the probe.